For many years now, there has been a trend away from the use of fossil fuels and towards renewable energy supplies for electricity generation. Fossil fuel supplies such as coal, oil and gas are depleting rapidly and the burning of fossil fuels is thought to be harmful to the environment. Renewable energy supplies such as wind, wave, tidal and solar supplies are effectively infinite and are not thought to cause as much harm to the environment. Accordingly, there is a continual shift towards these renewable energy supplies as they are sustainable and believed to be less detrimental to the environment.
However, there are some problems with many of the known renewable energy supplies and the apparatus for harnessing the renewable energy supplies. For example, wind power is deemed practical only in those areas that experience reliable, predictable winds above a certain wind strength all year round. The wind turbines used to harness the power of the wind are thought to be relatively noisy and it is undesirable to locate so-called “wind farms” near populated areas. Therefore, there are many areas where it is not possible or desirable to locate wind farms.
Furthermore, in relation to wave and tidal power, it goes without saying that these forms of renewable energy supplies require a coastline and access to the sea or an ocean in order to operate. It is thought in many quarters that wave and tidal renewable energy supplies are still several years away from being economically viable alternatives to fossil fuels. Accordingly, these renewable energy supplies are not available everywhere and even in those areas where they are available, they are not necessarily commercially attractive. Solar energy apparatus efficiency have improved and their price have dropped so that they are realistic alternatives to fossil fuels. However in order to derive these benefits, it is still necessary to have a high degree of sunlight all year round. Therefore, solar energy is not a realistic alternative in all locations.
One form of renewable energy supply that is becoming increasingly popular and attracting more attention is hydroelectric power generation that uses underwater “waterfalls” to generate the electricity. The advantage of this type of renewable energy supply is that it simply requires a body of water, even a lake or a pond, man-made or naturally occurring, and does not rely on waves, tidal flow or other climactic conditions to operate. Generally speaking, these devices comprise a generator with a turbine that is submerged under the water. Water from above is dropped onto the turbine causing the turbine to rotate and this movement is translated into electricity. The water that has been used to turn the turbine is released from the generator back into the body of water and recirculated. Therefore, there is an endless, continuous supply of electricity that may be produced from operating such a generator.
One apparatus for harnessing this energy and producing electricity is described in US patent application no. US200910230687 in the name of Robichaud, hereinafter referred to simply as Robichaud. Another apparatus for harnessing this energy and producing electricity is described in US patent application no. US2011/0260460 in the name of Rovinsky, hereinafter referred to as Rovinsky.
One common problem of all these devices is how to efficiently evacuate water that has passed over the turbine from the apparatus. If the water is allowed to dwell or build up in the apparatus, the turbine will eventually become flooded and will no longer rotate. Indeed, Rovinsky specifically mentions this as a problem of the corkscrew arrangement used to evacuate water from the apparatus disclosed in Robichaud. Rovinsky states that the corkscrew arrangement of Robichaud will be insufficient to remove the water from below the turbine. Rovinsky discloses several different arrangements for evacuating water from the apparatus.
It is an object of the present invention to provide a submersible hydroelectric generator apparatus and method of operating same that overcomes at least some of the problems with the known prior art. More specifically, it is an object of the invention to provide an apparatus and method that can effectively evacuate water from the apparatus. It is a further still object of the present invention to provide a useful choice for the consumer.